High-stability electron gun high-voltage power supply based on phase-shift full-bridge ZVS-PWM and control method

Abstract

The application discloses a high-stability electron gun high-voltage power supply based on a phase-shift full-bridge ZVS-PWM and a control method, and relates to the technical field of electron gun high-voltage power supplies. The high-voltage power supply comprises a three-phase rectification filtering module, a phase-shift full-bridge ZVS-PWM inverter module, a voltage transformation and rectification module, a multi-stage filtering module and a digital control and protection module. The control method comprises the following steps: performing two-stage detection on current, judging whether the current exceeds a preset value, quickly turning off a switch tube and executing recovery. The application has high efficiency, low output ripple, a two-stage protection mechanism and high safety.

Description

Technical Field

[0001] This invention relates to the technical field of electron gun power supply systems, and in particular to a high-stability high-voltage power supply and control method for electron guns based on phase-shifted full-bridge ZVS-PWM. Background Technology

[0002] The electron gun is one of the core components in coating equipment. It is mainly used to deposit target materials onto the surface of a substrate in a vacuum environment by means of electron beam evaporation or sputtering to form the required thin film layer.

[0003] There are currently two main technical solutions for high-voltage power supplies for electron guns: 1. SCR power supply: This method uses SCR thyristor choppers and power frequency transformers to step up the voltage, followed by filtering with inductors and capacitors. This solution has a simple structure, but it has inherent disadvantages such as large ripple, a large heat dissipation system, low efficiency (usually <70%), high energy consumption, and slow dynamic response.

[0004] 2. Conventional switching power supply: This solution adopts a high-frequency PWM hard-switching topology, which improves the size and efficiency, but has high switching losses and serious electromagnetic interference, affecting the operation of other precision sensors in the coating machine. It is difficult to reduce ripple under high voltage output (usually >2%). To meet the requirement of <1% ripple in high-end coating processes, extremely large filter components or complex circuits are required, which is costly. It has poor ability to cope with load changes such as electron gun arcing, and the efficiency improvement is limited.

[0005] In addition, when faced with the frequent instantaneous arc discharges during electron gun operation, the existing high-voltage power supplies have slow software protection responses, which can only reach the millisecond level. This can easily lead to equipment damage or process interruption, and the recovery process is cumbersome. Summary of the Invention

[0006] To address the aforementioned shortcomings, this invention provides a high-stability electron gun high-voltage power supply and control method based on phase-shifted full-bridge ZVS-PWM, which features high efficiency, low output ripple, a two-stage protection mechanism, and high safety.

[0007] In order to achieve the objectives of this invention, the following technologies are proposed: A high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM includes: Three-phase rectifier and filter module, with AC power connected to the input terminal; The phase-shifted full-bridge inverter module receives DC power output from the three-phase rectifier and filter module. It includes four switching transistors, each of which is connected in parallel with a protection diode and an output capacitor. The four switching transistors complement each other to form two arms of the full bridge. The transformer and rectifier module includes a transformer and a resonant inductor connected between one end of the primary side of the transformer and one bridge arm. The resonant inductor is used to make the output capacitor of the phase-shifted full-bridge inverter module and the leakage inductance of the transformer resonate. The other end of the primary side of the transformer is connected to another bridge arm, and the secondary side of the transformer is connected to a rectifier stack. The multi-stage filtering module includes two-stage filtering circuits. Each stage of the filtering circuit includes an inductor and a capacitor. The first-stage filtering circuit is connected in parallel to the output terminal of the rectifier stack. The second-stage filtering circuit is connected in parallel with the capacitor of the first-stage filtering circuit. The capacitor of the second-stage filtering circuit is connected in parallel to the output port of the entire high-voltage power supply, which is used to connect to the input terminal of the electron gun. The digital control and protection module includes a digital controller and a hardware comparator. The input of the digital controller is connected to a current detector, and the input of the hardware comparator is connected to an arc detector. The input of the digital controller is also connected to the hardware comparator. The digital controller is also used to adjust the phase difference between the two bridge arms. The output of the hardware comparator is connected to a CPLD, and the output of the CPLD is connected to an isolation drive module for turning off the switching transistor.

[0008] Furthermore, the input terminal is connected to 380V / 50Hz AC power, and the output terminal provides 10kV / 1A DC power.

[0009] Furthermore, the switching transistor is a 1200V / 50A IGBT, and its switching frequency is set to 25kHz.

[0010] Furthermore, the transformer's turns ratio is 30.

[0011] Furthermore, the rectifier stack includes four fast recovery diodes connected in a bridge topology.

[0012] Furthermore, the inductance and capacitance of the first-stage filter circuit are 50mH and 0.22μF, respectively.

[0013] Furthermore, the inductance and capacitance of the second-stage filter circuit are 30mH and 0.22μF, respectively.

[0014] Furthermore, the digital control and protection module also includes a safety interlock circuit connected to the digital controller. This circuit includes an AND gate circuit, which reads the vacuum level signal, water cooling signal, and door lock signal from the control system of the vacuum coating machine where the electron gun is located. When all signals are normal, the AND gate circuit is turned on, and the safety interlock circuit sends a signal to the digital controller, allowing the high-voltage power supply to start.

[0015] An electron gun high-voltage power supply control method, employing the aforementioned high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM, includes the following steps: S100: High-voltage power supply starts, providing DC output to the electron gun; S200: Waiting for the preset interval y; S300: The digital controller receives the current value detected by the current detector, and the hardware comparator receives the current sample value from the arc detector and compares it with 1.5A. S400: Determine whether the digital controller detects a current greater than 1.5A or the comparison result of the hardware comparator is greater than 1.5A. If yes, execute S500 and S600 simultaneously. If no, return to S200. The S500 and S600 respectively include: S510: The CPLD sends a blocking signal to the isolation driver module; S520: The isolation drive module shuts down all switching transistors; S610: The digital controller records faults; S620: Delay 5ms to wait for the arc to dissipate; S630: The output starts from 0V and increases the voltage at a rate of 500V / ms for soft start; S700: The digital controller determines whether the electron gun has been successfully restored. If yes, it returns to S200; otherwise, it executes S800. S800: Determine if there have been 3 consecutive recovery failures. If yes, execute S900; otherwise, return to S700. S900: Permanently shuts off the switch and issues an alarm, prompting manual intervention.

[0016] The beneficial effects of this technical solution are as follows: 1. Based on phase-shifted full-bridge ZVS-PWM, the overall efficiency is increased to over 90%, resulting in significant energy savings and reduced heat dissipation pressure.

[0017] 2. Stable output voltage and low output ripple meet the requirements of high-end coating processes.

[0018] 3. The digital control has a fast response and, combined with rapid hardware protection, can seamlessly cope with frequent arc discharges, improving coating production efficiency and film quality.

[0019] 4. It forms a soft switch, reduces device stress, and has a complete protection and interlock design, which greatly extends the life of the power supply and electron gun.

[0020] 5. Low switching noise and minimal interference to surrounding equipment, solving the efficiency and electromagnetic interference problems of high-power high-voltage switching power supplies. Attached Figure Description

[0021] Figure 1 The diagram shows the power main circuit architecture of a high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to an embodiment of this application.

[0022] Figure 2 The diagram illustrates the digital control and protection module architecture of the high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to an embodiment of this application, and its connection relationship with the phase-shifted full-bridge ZVS-PWM inverter module.

[0023] Figure 3 The diagram shows the main power circuit of a high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to an embodiment of this application.

[0024] Figure 4 The circuit diagram of the three-phase rectifier and filter module of the high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to an embodiment of this application is shown.

[0025] Figure 5 The waveform timing diagram of the high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM in the embodiment of this application is shown.

[0026] Figure 6 A flowchart illustrating the main steps of the high-voltage power supply control method for an electron gun according to an embodiment of this application is shown. Detailed Implementation

[0027] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0028] As one aspect of the present invention, such as Figures 1-5 The high-stability electron gun high-voltage power supply shown includes a three-phase rectifier and filter module, a phase-shifted full-bridge ZVS-PWM inverter module, a transformer and rectifier module, a multi-stage filter module, and a digital control and protection module.

[0029] Figure 4 The three-phase rectifier and filter module shown is connected to a 380V / 50Hz three-phase AC power supply at its input terminal. The module includes three rectifier sub-modules connected in parallel and a filter capacitor C0. The first rectifier sub-module is connected in series with VD1 and VD4, which is the A-phase input of the AC power. A The second rectifier module, connected in series with VD2 and VD5, inputs AC power in phase B, U. B The third rectifier submodule, connected in series with VD3 and VD6, inputs AC power in phase C, U. C The three-phase rectifier and filter module outputs DC voltage to the positive terminal BUS+ and the negative terminal BUS- of the DC bus after rectification and filtering. Specifically, it outputs 500VDC pulsating DC.

[0030] Figure 1 The diagram shows the architecture of the main power circuit, specifically the connection relationships between the four modules: the phase-shifted full-bridge ZVS-PWM inverter module, the transformer and rectifier module, and the multi-stage filter module. Figure 3 The specific components are shown and will be explained in detail below.

[0031] The phase-shifted full-bridge ZVS-PWM (Zero-Voltage Switching Pulse Width Modulation) inverter module receives DC power from the three-phase rectifier and filter module. The phase-shifted full-bridge ZVS-PWM inverter module includes four switching transistors (Q1~Q4). Q1 and Q2 are connected to the positive terminal of the DC bus BUS+, and Q3 and Q4 are connected to the negative terminal of the DC bus BUS-. Each switching transistor is connected in parallel with a protection diode (D1~D4) and an output capacitor (C1~C4). The switching transistors are 1200V / 50A IGBTs (Insulated-Gate Bipolar Transistors), and their switching frequency is set to 25kHz (the output ripple fundamental frequency is 50kHz). The four switching transistors complement each other to form two arms of the full bridge, namely the leading arm and the lagging arm, which are denoted as A and B in the circuit diagram, respectively.

[0032] The transformer and rectifier module includes a transformer with a turns ratio of 30 and a resonant inductor Lr connected between one end of the primary winding of the transformer and one bridge arm. The resonant inductor Lr is used to achieve resonance between the output capacitors (C1~C4) of the phase-shifted full-bridge inverter module and the leakage inductance of the transformer TX. The other end of the primary winding of the transformer TX is connected to the other bridge arm, and the secondary winding of the transformer TX is connected to a rectifier stack, which includes four fast recovery diodes D5, D6, D7, and D8 connected in a bridge topology. By utilizing the resonance of the transformer leakage inductance and the output capacitor, all power transistors can be turned on under zero-voltage conditions, significantly reducing switching losses and electromagnetic interference.

[0033] The multi-stage filtering module comprises two stages of filtering circuits. Each stage includes an inductor (L1, L2) and a capacitor (C5, C6). The capacitors are high-voltage polypropylene film capacitors. The inductance and capacitance of the first-stage filtering circuit are 50mH and 0.22μF, respectively, while the inductance and capacitance of the second-stage filtering circuit are 30mH and 0.22μF, respectively. The first-stage filtering circuit is connected in parallel to the rectifier output. The second-stage filtering circuit is connected in parallel with capacitor C5 from the first-stage filtering circuit. Capacitor C6 from the second-stage filtering circuit is connected in parallel to the output port of the entire high-voltage power supply, used to connect to the input of the electron gun Rload, providing 10kV / 1A DC power. This hybrid filtering design, targeting the high-frequency (twice the switching frequency) ripple of the ZVS-PWM output, uses a specially optimized LC filter to economically suppress ripple to within 1%.

[0034] like Figure 2The digital control and protection module shown includes a TMS320F28335 digital controller and an LM319 hardware comparator. The digital controller input is connected to a voltage detector and a current detector for sampling the output of the high-voltage power supply. The hardware comparator input is connected to an arc detector for sampling the arc of the electron gun. Since the arc detector has a faster response speed, typically less than 5μs (measured at 2μs in this embodiment), it can react quickly to sudden situations. The other two detectors have good stability and provide dual protection. The digital controller input is also connected to the hardware comparator. The digital controller is also used to adjust the phase difference between the two bridge arms. The hardware comparator output is connected to a CPLD (Complex Programmable Logic Device), and the CPLD output is connected to an isolation drive module for turning off the switching transistor. The digital control and protection module also includes a safety interlock circuit connected to the digital controller. This circuit includes an AND gate circuit, which reads the vacuum level signal, water cooling signal, and door lock signal from the control system of the vacuum coating machine where the electron gun is located. When all signals are normal, the AND gate circuit is turned on, and the safety interlock circuit sends a signal to the digital controller, allowing the high-voltage power supply to start, thus realizing hardware-level safety interlock.

[0035] Figure 5 The diagram illustrates the phase difference between the drive signals of the upper and lower arms of the full-bridge under phase-shift control (as shown by the vertical dashed lines in the figure for each pair), the resulting transformer primary voltage waveform, and the key resonance process waveform for achieving ZVS (zero voltage switching). The diagram also provides more detailed definitions for each switch: Q1 is the leading upper arm, Q2 is the lagging upper arm, Q3 is the leading lower arm, and Q4 is the lagging lower arm. Vab and Ip are the primary voltage and primary current of the transformer, respectively. +Vin is the positive input voltage, and -Vin is the negative input voltage.

[0036] In summary, this invention provides a high-efficiency, high-power-density, ultra-low output ripple (measured ≤1%) electron gun high-voltage DC power supply with microsecond-level arc suppression and intelligent recovery capabilities, thereby improving coating quality, process stability, and equipment reliability.

[0037] As another aspect of the present invention, such as Figure 6 The electron gun high-voltage power supply control method shown above uses the high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM, and includes the following steps: S100: When the safety interlock circuit sends a signal allowing the high-voltage power supply to start, the high-voltage power supply starts and provides DC output to the electron gun. S200: Wait for a preset interval y. In this embodiment, y = 10 μs. S300: The digital controller receives the current value detected by the current detector, and the hardware comparator receives the current sample value from the arc detector and compares it with 1.5A. S400: Determine whether the digital controller detects a current greater than 1.5A or the comparison result of the hardware comparator is greater than 1.5A. If yes, execute S500 and S600 simultaneously. If no, return to S200. The S500 and S600 respectively include: S510: The CPLD sends a blocking signal to the isolation driver module; S520: The isolation drive module shuts down all switching transistors; S610: The digital controller records faults; S620: Delay 5ms to wait for the arc to dissipate; S630: The output starts from 0V and increases the voltage at a rate of 500V / ms for soft start; S700: The digital controller determines whether the electron gun has been successfully restored. If yes, it returns to S200; otherwise, it executes S800. S800: Determine if there have been 3 consecutive recovery failures. If yes, execute S900; otherwise, return to S700. S900: Permanently shuts off the switch and issues an alarm, prompting manual intervention.

[0038] In terms of control strategy, digital control is combined with independent hardware-level arc fast protection circuit and software intelligent recovery logic; a hierarchical arc handling mechanism is adopted. The first-level protection is directly driven by high-speed comparators and hardware logic to achieve ultra-fast shutdown. The second-level recovery is performed by the DSP after protection, which executes an intelligent recovery process of delayed arc suppression, ramp soft start, and status determination, reducing manual intervention and improving process continuity.

[0039] The above are only some of the embodiments listed in this application and are not intended to limit this application.

Claims

1. A high-stability electron gun high-voltage power supply based on a phase-shift full-bridge ZVS-PWM, characterized in that, include: Three-phase rectifier and filter module, with AC power connected to the input terminal; The phase-shifted full-bridge inverter module receives DC power output from the three-phase rectifier and filter module. It includes four switching transistors, each of which is connected in parallel with a protection diode and an output capacitor. The four switching transistors complement each other to form two arms of the full bridge. The transformer and rectifier module includes a transformer and a resonant inductor connected between one end of the primary side of the transformer and one bridge arm. The resonant inductor is used to make the output capacitor of the phase-shifted full-bridge inverter module and the leakage inductance of the transformer resonate. The other end of the primary side of the transformer is connected to another bridge arm, and the secondary side of the transformer is connected to a rectifier stack. The multi-stage filtering module includes two-stage filtering circuits. Each stage of the filtering circuit includes an inductor and a capacitor. The first-stage filtering circuit is connected in parallel to the output terminal of the rectifier stack. The second-stage filtering circuit is connected in parallel with the capacitor of the first-stage filtering circuit. The capacitor of the second-stage filtering circuit is connected in parallel to the output port of the entire high-voltage power supply, which is used to connect to the input terminal of the electron gun. The digital control and protection module includes a digital controller and a hardware comparator. The input of the digital controller is connected to a current detector, and the input of the hardware comparator is connected to an arc detector. The input of the digital controller is also connected to the hardware comparator. The digital controller is also used to adjust the phase difference between the two bridge arms. The output of the hardware comparator is connected to a CPLD, and the output of the CPLD is connected to an isolation drive module for turning off the switching transistor.

2. The high stability electron gun high voltage power supply based on phase-shifted full-bridge ZVS-PWM of claim 1, characterized in that, The input terminal connects to 380V / 50Hz AC power, and the output terminal provides 10kV / 1A DC power.

3. The high stability electron gun high voltage power supply based on phase-shifted full-bridge ZVS-PWM of claim 1, characterized in that, The switching transistor is a 1200V / 50A IGBT, and its switching frequency is set to 25kHz.

4. The high stability electron gun high voltage power supply based on phase-shifted full-bridge ZVS-PWM of claim 1, characterized in that, The transformer has a turns ratio of 30.

5. The high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to claim 1, characterized in that, The rectifier stack includes four fast recovery diodes connected in a bridge topology.

6. The high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to claim 1, characterized in that, The inductance and capacitance of the first-stage filter circuit are 50mH and 0.22μF, respectively.

7. The high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to claim 1, characterized in that, The inductance and capacitance of the second-stage filter circuit are 30mH and 0.22μF, respectively.

8. The high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM according to claim 1, characterized in that, The digital control and protection module also includes a safety interlock circuit connected to the digital controller. This circuit includes an AND gate circuit, which reads the vacuum level signal, water cooling signal, and door lock signal from the control system of the vacuum coating machine where the electron gun is located. When all signals are normal, the AND gate circuit is turned on, and the safety interlock circuit sends a signal to the digital controller, allowing the high-voltage power supply to start.

9. A method for controlling a high-voltage power supply for an electron gun, characterized in that, The high-stability electron gun high-voltage power supply based on phase-shifted full-bridge ZVS-PWM as described in any one of claims 1 to 8 includes the following steps: S100: High-voltage power supply starts, providing DC output to the electron gun; S200: Waiting for the preset interval y; S300: The digital controller receives the current value detected by the current detector, and the hardware comparator receives the current sample value from the arc detector and compares it with 1.5A. S400: Determine whether the digital controller detects a current greater than 1.5A or the comparison result of the hardware comparator is greater than 1.5A. If yes, execute S500 and S600 simultaneously. If no, return to S200. The S500 and S600 respectively include: S510: The CPLD sends a blocking signal to the isolation driver module; S520: The isolation drive module shuts down all switching transistors; S610: The digital controller records faults; S620: Delay 5ms to wait for the arc to dissipate; S630: The output starts from 0V and increases the voltage at a rate of 500V / ms for soft start; S700: The digital controller determines whether the electron gun has been successfully restored. If yes, it returns to S200; otherwise, it executes S800. S800: Determine if there have been 3 consecutive recovery failures. If yes, execute S900; otherwise, return to S700. S900: Permanently shuts off the switch and issues an alarm, prompting manual intervention.

Images